US Secretary of State John Kerry has told Moscow that progress on the Ukraine crisis depends on a Russian troop pullback from Ukraine's borders.

"Both sides made suggestions of ways to de-escalate the security and political situation in and around Ukraine," Kerry told a news conference after meeting Russian Foreign Minister Sergei Lavrov for four hours in Paris.

"Any real progress in Ukraine must include a pullback of the very large Russian force that is currently massing along Ukraine's borders," Kerry said. "We believe these forces are creating a climate of fear and intimidation in Ukraine. It certainly does not create the climate that we need."

The two were seeking to hammer out the framework of a deal to reduce tensions over Russia's annexation of Ukraine's Crimea region. The Russian move into Crimea, following the ouster of Ukraine's pro-Russia president in February, has sparked the worst East-West confrontation since the Cold War ended two decades ago.

While there were no outlines of an agreement, the two sides agreed to keep talking and both said the Ukrainian government had to be part of the solution.

"Neither Russia, nor the United States, nor anyone else can impose any specific plans on Ukrainians," Lavrov told a separate briefing as quoted by the RIA news agency.

Washington is adamant that there could be "no decisions about Ukraine without Ukraine," Kerry told reporters, adding the

United States saw its role as creating conditions for negotiations between Moscow and Kiev.

Kerry made clear that Washington still considered Russian actions in Crimea to be "illegal and illegitimate."

The United States and European Union have issued two rounds of sanctions on Russia, including visa bans and asset freezes on some of Russian President Vladimir Putin's inner circle, to punish Moscow over its seizure of Crimea, a Russian-majority Black Sea peninsula.

Crimeans voted to secede from Ukraine and join Russia in a March 16 referendum dismissed as a sham by Western governments that say it violated Ukraine's constitution and was held only after Russian forces seized control of the region.

"The US and Russia have differences of opinion about events that led to this crisis, but both of us recognise the importance of finding a diplomatic solution and simultaneously meeting the needs of the Ukrainian people," Kerry said.

TROOP BUILDUP

The West has refused to recognise Crimea's absorption into Russia, although US officials acknowledge that the takeover of is not likely to be resolved soon. Instead, talks have focused on warning Moscow not to go farther into Ukraine.

US officials are deeply worried about the massing of what they estimate are up to 40,000 Russian troops on Ukraine's border, which is stoking concerns in Washington and elsewhere that Russia is preparing a wider incursion into Ukraine.

While Moscow has said the buildup is part of normal Russian exercises only, US President Barack Obama has described it as out of the ordinary that could be a precursor to other actions.

America's top general in Europe was sent back early from a trip to Washington in what the Pentagon on Sunday called a prudent step given Russia's "lack of transparency" about troop movements across the border with Ukraine.

General Philip Breedlove, who is NATO's Supreme Allied Commander Europe and head of the US military's European Command, arrived in Europe on Saturday evening. He had been due to testify before the US Congress this week.

US Defence Secretary Chuck Hagel considered Breedlove's early return "the prudent thing to do, given the lack of transparency and intent from Russian leadership about their military movements across the border," a Pentagon spokesman said.

Lavrov, speaking on Russian television on Saturday, said Moscow had "no intention" of invading eastern Ukraine and reinforced a message from Putin that Moscow would settle, at least for now, for control over Crimea.

Lavrov, added, however, that Russia was ready to protect the rights of Russian speakers, referring to what Moscow sees as threats to the lives of compatriots in eastern Ukraine.

Kerry said on Sunday the US side felt increased acknowledgement on Russia's part that Ukraine's transitional government was taking steps to address Moscow's concerns, including rights of minorities, constitutional reform and free and fair elections.

Lavrov told reporters: "We have agreed to work with the Ukrainian government and people to achieve progress in rights of minorities and linguistic rights," Interfax reported.

The Kerry-Lavrov meeting followed a phone call between Obama and Putin last week and came days before NATO foreign ministers hold meetings in Brussels on Tuesday and Wednesday that are likely to focus on Ukraine.